A cоmpаny thаt prоduces light bulbs аdvertises that the mean life expectancy оf its bulbs is at least 750 hours. The Consumers Union suspects that the mean life span of the light bulbs is in fact less than 750 hours. If it can prove this is the case, it plans to bring charges against the company for false advertising. An employee of the Consumers Union decides to investigate the mean life of the light bulbs produced by the company. She selects a random sample of 30 of this company's light bulbs, subjects them to normal use, and measures for each light bulb the number of hours until it burns out. The results for the sample of 30 bulbs are: Mean = 700 hours, and SD = 160 hours. Suppose the estimated standard error of the sample mean is 25 hours (actually it is not). Which of the following gives a 95% confidence interval of the mean life expectancy of the light bulbs produced by this company?